1. Field
The instant invention relates to a light and vision blocking device or system for blocking light from oncoming traffic. The light-blocking device utilizes vertically-oriented, elongated members attached to the top surface of a concrete highway barrier.
2. State of the Art
Light-blocking devices of various types have been utilized top highway median barriers. Typical of such devices are those disclosed in U.S. Pat. No. 4,088,415 (Syak) and U.S. Pat. No. 4,338,041 (Schmanski). Another device is a metal screen.
Each of the existing systems has advantages and disadvantages. Metal screens are permanently damaged by rocks, impacting vehicles, overhanging cargo, etc. and present a physical barrier to personnel as well, which can impede work associated with temporary detours and the like.
An assessment of the state of the art as of about 1981 is set forth in the Schmanski patent. The system of Schmanski, however, also has certain disadvantages. It is designed exclusively as a modular system with thin fiberglass reinforced plastic (FGRP) slats which are attached by a pair of L-shaped brackets to a FGRP runner which is then attached to a concrete median barrier. The runner is intended to absorb (dissipate) vibrational energy caused by the thin slats being buffeted by the wind or when struck by flying objects, truck mirrors or objects protruding from vehicles.
Because these light-blocking devices are used frequently on temporary detours adjacent to repair or construction work, the thin slats of Schmanski present a hazard to workmen whenever such slats are dislodged and become flying projectiles. Also, when these FGRP slats are struck at speeds of 30 MPH and above, they tend to shred at the tips. The fluttering of these tips from wind gusts caused by vehicles, especially large trucks, can be distracting to drivers. Also, the modular construction of Schmanski requires the whole unit (module) to be removed in order to replace a single slat which has been dislodged. Also, since the Schmanski slats are flat and thin, wind gusts tend to affect them greatly, causing constant flexing and waving, which not only puts constant stress on the system but the waving of the blades causes a distraction to drivers. Additionally, the metal brackets of Schmanski tend to take a permanently bent shape when the slats are struck by a protruding object on a vehicle at speeds greater than 30 mph.
The blunt-ended foils of Syak have several advantages over the Schmanski device, such as safety in the event a foil is dislodged. Also, the Syak foil can be individually used. The Syak foil, because it is fastened with bolts through the sidewall, may exhibit a tendency for the bolts to tear out the bolt hole when the foil is struck.